Featured Research

from universities, journals, and other organizations

New 'Quasiparticles' Discovered; May Pave Way Toward New Quantum Computer

Date:
June 5, 2008
Source:
Weizmann Institute of Science
Summary:
Scientists have demonstrated, for the first time, the existence of "quasiparticles" with the one quarter the charge of an electron. While charges with odd denominators have been seen, the new, quarter-charge quasiparticle is significant because it might form the basis of a novel type of quantum computer.

The device used to demonstrate the existence of 'quasiparticles' is shaped like a flattened hourglass, with a narrow 'waist' in the middle that allows only a small number of charge-carrying particles to pass through at a time.
Credit: Courtesy of Merav Dolev, Department of Condensed Matter Physics, The Weizmann Institute of Science

Weizmann Institute physicists have demonstrated, for the first time, the existence of 'quasiparticles' with one quarter the charge of an electron. This finding could be a first step toward creating exotic types of quantum computers that might be powerful, yet highly stable.

Fractional electron charges were first predicted over 20 years ago under conditions existing in the so-called quantum Hall effect, and were found by the Weizmann group some ten years ago. Although electrons are indivisible, if they are confined to a two-dimensional layer inside a semiconductor, chilled down to a fraction of a degree above absolute zero and exposed to a strong magnetic field that is perpendicular to the layer, they effectively behave as independent particles, called quasiparticles, with charges smaller than that of an electron. But until now, these charges had always been fractions with odd denominators: one third of an electron, one fifth, etc.

The experiment done by research student Merav Dolev in Prof. Moty Heiblum’s group, in collaboration with Drs. Vladimir Umansky and Diana Mahalu, and Prof. Ady Stern, all of the Condensed Matter Physics Department, owes the finding of quarter-charge quasiparticles to an extremely precise setup and unique material properties: The gallium arsenide material they produced for the semiconductor was some of the purest in the world.

The scientists tuned the electron density in the two-dimensional layer – in which about three billion electrons were confined in the space of a square millimeter – such that there were five electrons for every two magnetic field fluxes. The device they created is shaped like a flattened hourglass, with a narrow 'waist' in the middle that allows only a small number of charge-carrying particles to pass through at a time. The 'shot noise' produced when some passed through and others bounced back caused fluctuations in the current that are proportional to the passing charges, thus allowing the scientists to accurately measure the quasiparticles’ charge.

Quarter-charge quasiparticles should act quite differently from odd fractionally charged particles, and this is why they have been sought as the basis of the theoretical 'topographical quantum computer.' When particles such as electrons, photons, or even those with odd fractional charges change places with one another, there is little overall effect. In contrast, quarter-charge particle exchanges might weave a 'braid' that preserves information on the particles’ history. To be useful for topologically-based quantum computers, the quarter-charge particles must be shown to have 'non-Abelian' properties – that is the order of the braiding must be significant. These subtle properties are extremely difficult to observe. Heiblum and his team are now working on devising experimental setups to test for these properties.

Prof. Moty Heiblum’s research is supported by the Joseph H. and Belle R. Braun Center for Submicron Research. Prof. Heiblum is the incumbent of the Alex and Ida Sussman Professorial Chair in Submicron Electronics.


Story Source:

The above story is based on materials provided by Weizmann Institute of Science. Note: Materials may be edited for content and length.


Journal Reference:

  1. Dolev et al. Observation of a quarter of an electron charge at the nu = 5/2 quantum Hall state. Nature, 2008; 452 (7189): 829 DOI: 10.1038/nature06855

Cite This Page:

Weizmann Institute of Science. "New 'Quasiparticles' Discovered; May Pave Way Toward New Quantum Computer." ScienceDaily. ScienceDaily, 5 June 2008. <www.sciencedaily.com/releases/2008/06/080602103355.htm>.
Weizmann Institute of Science. (2008, June 5). New 'Quasiparticles' Discovered; May Pave Way Toward New Quantum Computer. ScienceDaily. Retrieved October 20, 2014 from www.sciencedaily.com/releases/2008/06/080602103355.htm
Weizmann Institute of Science. "New 'Quasiparticles' Discovered; May Pave Way Toward New Quantum Computer." ScienceDaily. www.sciencedaily.com/releases/2008/06/080602103355.htm (accessed October 20, 2014).

Share This



More Computers & Math News

Monday, October 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Facebook Says The DEA's Fake Accounts Go Too Far

Facebook Says The DEA's Fake Accounts Go Too Far

Newsy (Oct. 19, 2014) Facebook says the DEA violated its Terms of Service and that such impersonations damage the integrity of the site. Video provided by Newsy
Powered by NewsLook.com
Court Ruling Means Kids' Online Activity Could Be On Parents

Court Ruling Means Kids' Online Activity Could Be On Parents

Newsy (Oct. 17, 2014) In a ruling attorneys for both sides agreed was a first of its kind, a Georgia appeals court said parents can be held liable for what kids put online. Video provided by Newsy
Powered by NewsLook.com
For Google, Even A $16.5 Billion Earnings Report Is A Miss

For Google, Even A $16.5 Billion Earnings Report Is A Miss

Newsy (Oct. 17, 2014) Analysts were expecting more, but Google’s ad growth slowed on the quarter and the company is spending more of its money. Video provided by Newsy
Powered by NewsLook.com
Obama Signs Cybersecurity Order, Wants Safer Payments

Obama Signs Cybersecurity Order, Wants Safer Payments

Reuters - US Online Video (Oct. 17, 2014) President Barack Obama announces details of a new executive order designed to make federal payments safer following recent massive data breaches. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins